The presence of two orthogonally polarized emission modes in pulsar profiles has been known since the 1970s [1]}. If the dominant emission mode changes across the profile, a 90 jump in the PA swing is observed (e.g. PSR J1110–5637 in Figure REF ). If we examine the profiles of all the pulsars in the `RVM' and `flat' class, we find that at least one orthogonal jump occurs in 139 out of 502 cases (28%). We see that the prevalence of orthogonal jumps is lower in the pulsars with a high \(\dot{E}\) , with only 8 out of 81 pulsars with \(\dot{E} > 10^{34}\)  erg s\(^{-1}\)  showing this effect. We note that the fraction of pulsars showing an orthogonal jump should be considered a lower limit. Some of the pulsars in the `non-RVM' category show `resolved' jumps (e.g. PSR J0738–4042; see Figure REF ) and some show jumps which differ from 90 by enough to render the RVM fit poor.
